This invention will be particularly discussed in relation to its application for the repair of abdominal aortic aneurysms and particularly aneurysms adjacent the iliac bifurcation, aneurysms in the thoracic arch and aneurysms in other parts of the aorta where there are branched vessels. The invention is, however, also applicable to other body lumens in humans or animals where a bifurcation or branch vessel is present.
In this specification when referring to the vasculature of a patient the term proximal will be used to define that position or part of a component which is closest to the patient's heart and distal will be used for that position or part of a component which is furthest from the patient's heart. It will be realized that for other body lumens then corresponding terminology such as cranial and caudal should be understood.
A typical bifurcated modular prosthesis usually has a body and a short leg and a long leg extending from the body. Deployment of such a prosthesis at the iliac bifurcation requires placement of the prosthesis in the aorta with the short leg completely contained within the aorta and the long leg extending into one of the iliac arteries. An extension leg is then inserted through the contra-lateral iliac artery into the short leg to complete the bifurcated prosthesis.
Often it is desirable to place the bifurcation of the prosthesis close to the aortic bifurcation but still have enough space for overlap of the extension leg with the short leg in the aorta. In other cases, a graft may need to be placed within another already placed graft and in such case there may only be a short length of grafted aorta to work in. In still other cases there may not be enough space to fit a prosthesis between the renal arteries and the iliac bifurcation and hence for these various situations a new form of bifurcated graft is required.
In the thoracic arch of a human or animal patient there are a number of very important branch arteries which, when treating an aneurysm incorporating the thoracic arch using an endovascular graft, must not be occluded. It is difficult, however, to deploy a stent graft into the thoracic arch with side arms which extend into one or more of the branch arteries from the thoracic arch.